There have been reports in the scientific literature concerning the preparation of 6-iodocholesterol, radiolabelled 6-iodocholesterol and the use of such compounds in organ visualization of mammals. For example, the article "Labeling of 6-iodocholesterol with I-131" BO-Li, 3rd Int. Symp. Radiochem. St. Louis, 1980 p. 112 describes the preparation of 6-iodocholesterol labelled with I-131. The article "I-6-iodocholesterol, An Agent for Imaging the Adrenal Gland", Jixaio and Rursen, Chinese Med. Jour. 62, 237 (1979) describes the preparation of radiolabelled 6-iodocholesterol and its use as as agent which concentrates in the adrenal glands of mammals is of utility in the diagnostic investigation of adrenal gland function.